Thermostat-controlled circuits



March 5 1935. R. J. PARSONS 1,993,522

THERMOSTAT CONTROLLED CIRCUITS Filed Sept. 30, 1932 2 V 1a, 4a

INVENTOR Robert J. Parsons BY ATTORN Patented Mar. 5, I935 ED STATES PATENT OFFICE THERMOSTAT-CONTROLLED CIRCUITS Robert J. Parson's, Schenectady, N. Y., assignor to Consolidated Car-Heating Company, Inc., Albany, N. Y., a corporation of New York Application September 30, 1932, Serial No. 635,671-

2 Claims. (01. 175-320) For a detailed description of the present form resistor L, which by-passes the coil C. It will of my invention, reference may be had to the be observed that the grounded resistance E is following specification and to the accompanyconnected to the circuit between the coil G and ing drawing forming a part thereof, said drawthe branch wires 16 and 17. The coil C con- 5 ing being a diagrammatic illustration of a circuit trols a circuit closer M which is included in a 5 modified to conform to the invention. branch circuit comprising conductor 18, so con- My invention arose from experience with a nected with the circuit through resistor D as to standard thermostatic equipment which gave by-pass the coil G, and also includes contacts trouble because of the frequent giving out of 19 and 20, and conductor 21 which joins the thermostat tubes constantly requiring their rebranch wires 16 and 17 at a position between 10 placement. The reason for such trouble was the coil C and the grounded resistor E. The not apparent, but, by a series of tests the cause coil C is wound upon the tube K of heavy was finally ascertained, and the device of the copper. present application has proved to be an effective From the foregoing, it will be noted that the remedy therefor. I speak of the trouble as a relay C is connected to the circuit at a point 15 giving out of the thermostat. By this I do not between the circuit breaker G and the therlimit myself to the breakage of its glass tube mostat A, while a 250-ohm resistor L, which but include as more important the formation shunts the coil C is also permanently connected of a scum or oxide on top of the mercury causin the circuit.

20 ing the mercury to stick in the bore of the ther- In operation, assuming the space that is to 20 mometer. be heated is cold, the circuit from trolley H This mysterious failure of the thermostat to will be through resistor D, coil G, and resistproperly function necessitated constant close inance E to ground. When the coil G is energized spection, and involved the expense of frequent the circuit breaker is operated to close the cirreplacements of the defective instruments. In cuit directly from trolley H to heater F. As 25 the course of experiments initiated to discover the temperature rises, the thermostatAwill eventhe cause of said failing, I ascertained that it tually close its circuit, whereupon current will was due to inductive disturbances at the relay first flow from coil G through the branch circoil controlled by the thermostat which occurred cuit indicated by wire 15, branch wires 16 and when the trolley passes under a section insula- 17 (including coil C and resistance L), con- 30 tor in the trolley wire, or when the line-breakductor l4 and thermostat to ground. The iner on the car was tripped by excessive speed. stant that coil C is energized, the circuit is My invention lies in the discovery of the cause closed at M, whereupon the current from trolley of the trouble and the application of certain H will by-pass the coil G and will flow through remedial expedients to the cause, towit, the wire 18, circuit closer M to the branch wires 16 35 employment in the relay which the thermostat and 17 and thence to the thermostat and ground, controls of a copper tube on which the coil through the course already described. As long thereof is wound, and a rearrangement of its as coil C is energized, the circuit which byconnection in a way to reduce the amperes and passes coil G will be maintained, but upon breakvolts of the relay. ing of the circuit at the thermostat, the coil C 40 Referring to the drawing, F designates the becomes deenergized, thereby breaking the byheater which receives current from the trolley passing circuit at the circuit closer M, and re- H through the conductor 10, line breaker B and energizing the coil G, so as to again close the conductor 11. The circuit breaker is controlled circuit'to the heater F.

by a circuit from the trolley H, which includes While it has not been definitely ascertained 45 reSiStOr D, fuse 0011 G av n a o 6011- just Why this circuit arrangement corrects the nected with the movable member of the circuit above described conditions which impair and in breaker, and resistance E, which latter is fact actually prevent the proper functioning of grounded. The thermostat A has one terminal the thermostat, it is believed to be due to the grounded in the usual manner at 13, the other reduction of inductive kick in the coil C pro- 50 terminal being connected with the conductor duced by the absorption of self-inductive ef- 14 which is connected with one end of coil G fects in the coil by the copper tube K, and by by means of a conductor 15, and intermediate the reduced voltage of the coil C upon the therbranches 16 and 17. The branch 16 includes mostat contacts produced by these aforesaid conthe relay coil C and the branch 17 includes a nections. The said voltage is reduced to ap- 55 proximately 22 volts in the new organization as compared with 100 volts in the old one. This theory, as above expressed, is subject to modification and therefore is not intended to be bind- What I claim as new and desire to secure by Letters Patent is:

1. In a thermostatic relay circuit, a relay magnet consisting of a coil wound upon a tubular metallic core capable of absorbing self-inductive effects of said coil, a grounded thermostat connected with one end of the coil, means connecting the other end of the coil with a source of electrical energy, and voltage reducing means lay-passing the coil and also in circuit with said thermostat and in series with said cource of electrical energy.

2. In a thermostatic relay circuit, a relay magnet consisting of a coil wound upon a tubular metallic core capable of absorbing self-inductive eifects of said coil, means providing a source of electrical energy, means connecting said coil in series with said thermostat and said source of electrical energy, and a branch circuit also in series with said source of energy and said thermostat and by-passing said coil, said branch circuit including a resistance.

ROBERT J. PARSONS. 

